Device for Operations in Proximity of an Underwater Installation

ABSTRACT

A seabed positioned subsea installation comprise processing equipment. The subsea installation is provided with at least one guide way and at least one manipulator device. The base of the manipulator device is movably attached to the at least one guide way, and the subsea installation further comprises a frame extending over the processing equipment.

This invention relates to a manipulator device for operation of a subsea installation and its processing equipment. More particularly the invention relates to a manipulator device which is permanently installed on a subsea installation to be able to carry out subsea inspection, maintenance, modification and surveillance of the subsea installation and its processing equipment.

The petroleum industry applies an increasing number of remotely controlled subsea installations for production of oil and gas. These are partly placed at great ocean depths. In order to be able to carry out inspection, maintenance and repair work on such installations, and also assist in well intervention, that is work to be carried out in the well, intervention vessels are used. For help in this work, remotely controlled vessels, so-called ROVs, operated by an operator on the support ship on the surface, are also used. The intervention vessel can also be the support vessel for the ROV. The support vessel with the ROV must be mobilised to the right place, and it takes time to manouvre the ROV from the surface down and back up, and as there might be poor weather conditions, the support vessel/intervention vessel might remain waiting. This might lead to various types of operational deviations and increased risk. Work to be carried out on such installations might therefore be unfortunately time consuming compared to the weather windows available, with the extra costs this results in. The problem is intensified by the typical lack of adapted intervention vessels to operate subsea installations of this type. Thus alternative technology that strongly contributes to reducing vessel time on the individual installation, will be both cost saving and risk reductive.

Work tasks carried out by an ROV in connection with well interventions on a subsea installation, might for instance be to prepare the subsea installation before the well intervention tool is led from the intervention vessel to the wellhead. Such work might comprise of opening of gates in the subsea installation over the wellhead, closing of valves and opening of valves. Similar work, but in the opposite order, can be carried out after completion of the well intervention. The ROV is also used for carrying out subsea inspection, maintenance, modification and surveillance of the subsea installation and its processing equipment.

In some jurisdictions it is an official requirement that subsea installations are provided with a protective frame extending over the subsea installation. The frame can protect against trawling so that the subsea installation is so-called over-trawlable. The frame can also protect the subsea installation and its processing equipment against for instance anchors and objects failing overboard from a vessel that is above the subsea installation.

Patent document NO 160736 discloses a subsea installation without a protective frame over the subsea installation. The subsea installation is provided with elongated rails. A rather big, loadbearing, attended autonomous subsea vessel can be led over the installation and be positioned upon the rails with legs protruding down from the subsea vessel. The subsea vessel can move sideways along the rails on the down-protruding legs. The subsea vessel is not arranged to be able to carry cut work on a subsea installation provided with a protective frame over the subsea installation.

Patent document NO 160736 discloses a subsea installation with a protection fender, but without any protective frame over the subsea installation. The subsea installation is in its lower part provided with a rail inside of the protection fender and which surrounds the production collecting pipes. A buoy is released from the rail and pulls with it a line up to the surface. A manipulator can be lowered down to the subsea installation by pulling itself down along the line to meet the rail, and it is movably attached upon the rail. The manipulator can carry out various types of work tasks on the subsea installation. Patent document NO 139323 also discloses a subsea installation without any protective frame over the subsea installation. The subsea installation is in its lower part provided with rails encircling the subsea installation. A buoy is released from the rails and pulls with it a line tip to the surface. A manipulator can be lowered down to the subsea installation by pulling itself down along the line to meet the rails, and it is removeably attached upon the rails. The manipulator can carry out various work tasks on the subsea installation. A protective frame over the subsea installation will for both solutions shown, prevent a buoy from rising freely up from the rail, and that a manipulator could be lowered down upon the rail.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art, or at least to provide a useful alternative to prior art.

The object is achieved through the features which are specified in the description below and in the claims that follow.

The invention relates to a seabed positioned subsea installation comprising process equipment; the subsea installation is provided with at least one guide way and at least one manipulator device; the base of the manipulator device is moveably attached to the at least one guide way; and where the subsea installation further comprise of a frame extending over the process equipment.

The base of the manipulator device can be releasably attached to the guide way. The guide way can comprise of at least one elongated guide way element.

The frame might be provided with gates in its upper part. The gates will be able to protect the processing equipment against failing objects. The guide way might be attached to the frame's upper part in operational position.

The manipulator device can be provided with energy from the energy source of the subsea installation. The manipulator device can be provided with communication means arranged to be able to remotely control the manipulator device.

In the following, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

FIG. 1 shows a perspective view of a schematic drawing of a subsea installation positioned on a seabed where the subsea installation is provided with a manipulator device in accordance with the invention;

FIG. 2 shows simplified schematic top view of the upper part of the frame of a subsea installation, and with two manipulator devices positioned in an alternative embodiment compared to that shown in FIG. 1;

FIG. 3 shows an alternative embodiment compared to FIG. 2; and

FIG. 4 shows a further alternative embodiment compared to FIG. 2.

In the drawings the reference numeral 1 indicates a manipulator device in accordance with the invention. A subsea installation 2 positioned on a seabed 9, comprises of a protective frame 20. The frame 20 surrounds one or more processing equipment 3 and extends over the process equipment 3. The frame 20 is in its upper part 21 provided with an elongated guide way 4. The manipulator device 1 comprise of a base ID which is releasably attached to the guide way 4 and arranged to be able to be moved along the guide way 4 in its longitudinal direction as indicated with an open double arrow in the FIGS. 2-4.

The base 10 of the manipulator device I is of per se known type and can be constituted of a foundation or a trailer. The base 10 is provided with an arm 11. In the free end part 13 of the arm 11, the arm 11 is provided with a wrist 15 and a tool holder 17 which is attached to the wrist 15. The base 10 and/or the arm 11 is/are rotatably arranged in relation to the guideway 4 as indicated by the bowed, double arrow in the FIGS. 2-4. The arm 11 can be hinged and rotatably attached to the base 10. The arm 11 can be made up of various units like for instance a two-hinged arm 11 with a proximal arm and a distal arm. The arm 11 can also be a three-hinged arm 11 with a proximal arm, a middle arm and a distal arm. The arm 11 can be arranged to be able to be folded up, such that the folded length of the arm 11 corresponds to the length of the longer of the distal, middle or proximal arms. By rotation of the units of the arm 11 relative to each other and to the base 10, the tool holder 17 can be moved back and forth relative to the base 10 as indicated by a straight double arrow in the FIGS. 2-4. The tool holder 17 can also be moved up and down relative to the base 10. With that, the arm 11 is able to relocate the tool holder along the x-y-z axes. The wrist 15 can be arranged to rotate the tool holder 17 relative to one, two or three axes in a per se known way. In the figures, the base 10, the arm 11, the wrist 15 and the tool holder 17 are shown schematically only.

A subsea installation 2 of this type is known from and used in the petroleum industry. The processing equipment 3 can comprise of wellheads with production valves, choke valves, closing valves and blow out valves. The processing equipment 3 can also comprise of separation devices, compressors and pumps. The processing equipment 3 might be provided with its own mooring base (not shown) which is surrounded by a frame 20, or the processing equipment 3 can be secured to the frame 20 as shown in FIG. 1. The frame 20 protects the processing equipment 3 against for example damage caused by a trawl. The frame 20 can be provided with a trawl protector 23, which makes the subsea installation 2 over-trawlable when the installation is located at depths where trawling occurs. The upper part 21 of the frame 20 can be provided with gates 25 as shown in FIG. 1. These gates 25 are left out in the schematic FIGS. 2-4. The gates 25 may be hinged to the upper part 21, and the manipulator device 1 with its arm 11 and tools placed in the tool holder 17, can open and close the gates 25 from inside of the frame 20.

The guide way 4 in the upper part 21 of the frame 20 can comprise of one guiding element 40 as shown in figures 2 and 4. In an alternative embodiment the guide way 4 might comprise of two guiding elements 40, 40′ side by side, as shown in figure 2. The base 10 of the manipulator device 1 is releasably and movably attached to the guide way 4 with for instance a traverser carriage (not shown) of per se known type arranged to be led along one guiding element 40 or in a guiding element 40, as for example a profiled rail. The base 10 can in an alternative embodiment be provided with a carriage (not shown) running along two guiding elements 40, 40′. The manipulator device 1 can be arranged to be releasable from the guide way 4 by means of for instance a remotely controlled subsea vessel, a so-called ROV. Subsequently the ROV takes the manipulator device 1 to the surface in order for, for example, inspection, maintenance, repair work and/or modification of the manipulator device 1 to be carried out. The manipulator device 1 can thereafter be fitted into the subsea installation 2 by means of an ROV.

The manipulator device 1 can be arranged to be provided with energy from the same energy supply as the subsea installation 2 is served by. The energy supply can be provided through an electric cable 5. The transfer of energy from the subsea installation 2 to the manipulator device 1 can take place through a cable (not shown) or by induction.

The manipulator device 1 can be arranged to foe remotely controlled. This can foe done in a per se known way through radio communication or through cabled communication. FIG. 1 shows a communication cable 6 for this purpose. The manipulator device 1 can foe arranged to function autonomous in the sense that it on signal or work order carries out a predefined set of actions and operations according to a time pattern. The manipulator device 1 can also be arranged to be controlled in real time by an operator on land or on board a vessel (not shown), The manipulator device 1 or the subsea installation 2 might, for this purpose, be provided with at least one camera (not shown). A person skilled in the art will understand that the manipulator device 1 is provided with the necessary motors, actuators and other equipment in order to be able to carry out its work tasks. This will not be further discussed.

When there is a need for carrying out work on the subsea installation 2, a work order is sent to the manipulator device 1. This might for instance be to prepare the subsea installation 2 for well intervention. The manipulator device 1 will then, by means of its arm 11 and tools on the tool holder 17, carry out the same work tasks as an ROV. This can be done independently of the weather on the surface. The manipulator device 1 can move along the guide way 4 and will, by means of the movable arm 11, be able to carry out all relevant work operations all over the subsea installation. With that, an intervention vessel may begin straight on with the well intervention work at arrival on the work site. 

1. A seabed positioned subsea installation comprising processing equipment; wherein the subsea installation is provided with at least one guide way and at least one manipulator device; the base of the manipulator device being movably attached to the at least one guide way, wherein the subsea installation further comprises an over-trawlable frame extending over the processing equipment and wherein the guide way is positioned within the frame.
 2. The subsea installation in accordance with claim 1, wherein the base of the manipulator device is releasably attached to the guide way.
 3. The subsea installation in accordance with claim 1, wherein the guide way comprises at least one elongated guiding element.
 4. The subsea installation -in accordance with claim 1, wherein the frame in its upper part provided with gates.
 5. The subsea installation in accordance with claim I, wherein the guide way is attached to the upper part of the frame in operation position.
 6. The subsea installation in accordance with claim 1, wherein the manipulator device is provided with energy from the energy supply of the subsea installation.
 7. The subsea installation in accordance with claim 1, wherein the manipulator device is provided with communication means arranged to remotely control the manipulator device. 